The invention relates to a sampling system for monitoring volatile releases and, more particularly, a system that provides for a modifiable headspace used for measuring a concentration of volatiles emanating from a surface.
Measuring odors and bacteria plays an important role in the field of quality inspection, for example, when the freshness of perishable foods being shipped is to be evaluated. Other examples include control of fermentation and classification by grade of food, such as seaweed, coffee, alcoholic beverages or the like in accordance with volatile concentrations. For such quality inspections, it is generally important to measure individual volatiles as well as the total concentration of volatiles. Volatiles are airborne releases from a surface that indicate a level of spoilage and/or contamination. They are known to have an odor or be odorless. Multiple surfaces have volatile releases. Besides food surfaces, waste, perishables, and non-perishables alike emit volatiles.
Conventionally, the above-mentioned quality inspections have been carried out by odor organoleptic tests. For example, by human sense of smell. Such inspections are typically possible for those who have a keen sense of smell and taste and are well trained to perform such inspections. However, such training is generally time consuming. Further, the results of the inspections may differ depending upon the physical conditions of the inspector. Moreover, odorless volatiles would be undetected.
Devices for collecting air samples from a food""s surface for measuring concentrations of volatiles were developed to overcome the disadvantages of the human nose. These devices typically require the air samples to reach equilibrium, or have a consistent concentration of volatiles throughout the samples, in order to provide accurate and reproducible measurements. In order to reach equilibrium, one may wait a sufficient amount of time for the volatile releases to self disperse evenly throughout an air sample. Therefore, the response time for an air sample to be collected is typically dependent upon the size of the sample.
Known devices for collecting air samples typically include rigid containers and flexible bags. Overall, rigid containers were found to provide reproducible results because the headspace, the clearance between the surface of the sample and container was advantageously fixed. However, smaller samples of food generally had slow response times due to a large headspace whereas larger samples had quick response times. Hence, the containers did not provide consistent response times among varying samples.
Flexible bags overcame the disadvantage of rigid containers in that they generally captured air samples of varying volumes around odd-shaped samples quicker because the headspace may be advantageously adjusted to each sample size. Such odd-shaped samples of foods include chicken legs, fish fillets, ribs, and the like. However, bags do not have structural integrity and collapse and sometimes stick to the surfaces they are covering, thereby further reducing the air samples to those sample surfaces that are not stuck to a collapsed bag. Because the bag may stick to the sample in unpredictable and asymmetric locations, a larger, localized headspace may require a longer time to reach equilibrium than a smaller headspace on the same piece of sample. This disadvantageously affects reproducibility and results in inconsistent response times.
What is desired, therefore, is a device that minimizes air samples for measuring volatile releases from variably sized surfaces. What is also desired is a device having structural integrity and providing an adjustable headspace. What is further desired is a device for providing reproducible measurements of volatiles.
Accordingly, it is an object of the invention to provide an adjustable housing for covering a surface of a sample.
It is another object of the invention to provide a housing that minimizes the headspace over the sample in order to provide an air sample of volatiles having the desired concentration of volatile releases in a shorter period of time.
It is a further object of the invention to provide a housing having at least one device for adjusting the headspace.
It is still another object of the invention to provide a housing for covering a localized area of the sample surface.
These and other objects of the invention are carried out by an apparatus having a modifiable headspace for measuring a concentration of volatile releases from a sample surface. The apparatus includes a collapsible housing for containing the air sample and a plurality of spacers between the housing and sample surface for separating them from one another. The plurality of spacers further provides an adjustable distance between the housing and the sample.
The plurality of spacers may be attached one at a time or, if clustered together in tandem or groups, attached several at a time. This permits optimum flexibility because one may adjust the distance between the housing and sample at any location on the sample surface. This adjustment is not readily available when the spacers are integrally formed with the housing at predetermined locations.
The apparatus further includes an outlet for permitting the air sample to be extracted from the housing and an inlet for permitting air to enter the housing, thereby facilitating the extraction.
To determine the quantity of volatile releases present in the headspace, a sensor or other handheld instrument for testing may be connected to the outlet.
The housing may be flexible and have no structural integrity, thereby requiring the plurality of spacers to prevent the housing from collapsing onto the sample surface. The housing may further be a flexible bag made of a leak proof material to prevent volatile releases from escaping.
In another embodiment, the plurality of spacers is integrally formed with the collapsible housing. This facilitates the application of the spacers because by merely covering the sample surface with the housing, the spacers are simultaneously applied as well.
In another embodiment, the housing covers the sample surface in a localized area as opposed to covering the entire surface. This embodiment is particularly useful where the sample cannot fit within the housing or when localized testing of the sample surface is desired. The housing for covering a localized area of sample may be a funnel or container.
In another embodiment, an air sampling kit is provided further including a tray. The tray is for holding and handling the sample and for further transporting the kit from one location to another.
In another aspect of the invention, a method for measuring a concentration of volatile releases is provided. The method includes covering a sample with a housing, attaching a plurality spacers to the sample for separating the housing from the surface, adjusting the headspace or volume of air between the sample and housing, and extracting an air sample for testing.